Last reviewed and revised by Faculty of Harvard Medical School on January 24, 2013
By Harvey B. Simon, M.D.
Harvard Medical School
Sexually transmitted infections (STIs) have plagued men (and women) since the beginning of recorded history. About 19 million people in the United States are infected each year. Nearly half of them are adolescents and young adults. And with the rise of HIV/AIDS, STIs have joined the ranks of killers. Fortunately, STIs can be prevented and treated.
What Are STIs?
STIs are infections that are passed from person to person by sexual contact usually through vaginal intercourse. But STIs can also be spread by oral and anal sex, and contaminated needles and blood products. Pregnant women can also pass STIs to their newborns.
There are more than 30 infections that can be transmitted sexually. The most important ones that affect men are caused by either bacteria (gonorrhea, syphilis, and chlamydia) or viruses (HIV/AIDS, genital herpes, hepatitis A, B and C, and human papillomavirus or HPV).
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Who Gets an STI?
Anyone who is sexually active can get an STI. Some men are at much higher risk than others, including men who:
- Have multiple or new sexual partners
- Live in large cities
- Have contact with sex workers
- Have sex with men
- Use illicit drugs
- Have had a previous STI
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Screening for STIs
STI testing can help diagnose STIs as early as possible. This is vital so treatment can start as soon as possible and you can prevent the spread of the infection to others. Consider getting tested if you:
- Have been exposed to an STI
- Have symptoms that may indicate an STI, such as genital sores or ulcers, discharge from the penis or burning on urination
- Are at high risk for an STI even without symptoms. This is especially important for young, sexually active people and for men who have sex with men.
There are several types of screening tests for men. They include:
- Blood tests for HIV, syphilis and hepatitis
- Urine tests for chlamydia and gonorrhea
- Bacterial cultures (a lab test to see if bacteria grow) for gonorrhea
Your test results should be strictly confidential. If you test positive for an STI, get treated right away. Notify all of your sexual partners immediately, so they can get treated. Stop all sexual activity while you are being treated.
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The only sure way to prevent STIs is to not have sex or to have sex with only one partner who is healthy.
As simple as this may sound, millions of Americans still get STIs every year. But practicing safer sex offers substantial protection from STIs.
The proper use of a male condom is the best way to protect yourself from STIs. Use one each and every time you have sex. Put the condom on before any sexual contact occurs. Latex condoms are best. If you or your partner is allergic to latex, use a polyurethane condom. Animal-skin condoms do not prevent infections.
The female condom may also help, but information about its effectiveness is much less complete. Other contraceptive methods do not protect against STIs.
Vaccines and other medications
Vaccines are available for HPV and hepatitis A and B. Preventive antibiotics can protect people newly exposed to chlamydia, gonorrhea, or syphilis. People with genital herpes can take antiviral drugs to protect their partners.
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Seven Common STIs
Chlamydia is the most common STI in America. There are an estimated 2.8 million new cases each year.
Cause: A tiny bacterium (Chlamydia trachomatis) that cannot grow in ordinary bacterial cultures but can be identified in urine samples or on swabs of the genital tract. Different strains of chlamydia that are not spread by sex can cause pneumonia and other illnesses.
Symptoms: A thin discharge from the penis, often with itching or burning on urination. Some men don't have any symptoms; they are usually diagnosed on the basis of exposure and lab tests.
Treatment: Most patients will be cured by a single dose of the antibiotic azithromycin or a one-week course of doxycycline.
About 700,000 people in the United States are diagnosed with gonorrhea each year, but because many people with gonorrhea do not seek treatment, the total number of cases may be much higher.
Cause: A bacterium that can be seen under a microscope, cultured in a laboratory, or detected in urine tests.
Symptoms: A pus-like discharge from the penis and burning on urination. In addition, the bacterium may invade the blood, especially in women, to cause fever, a rash and painful joint inflammation. But many women and some men aren't aware they are infected and can spread the infection without knowing it.
Treatment: Antibiotics can cure gonorrhea, but the bacterium has become resistant to many drugs over the years. Experts now recommend treatment with an injection of ceftriaxone; if that's not possible, the oral antibiotic cefixime may be used. Because chlamydia and gonorrhea often occur together, patients with either one of these infections should be treated for both unless tests have ruled out a second infection.
Although syphilis has become relatively uncommon in the United States, cases have steadily increased over the past few years.
Cause: The special type of bacterium that causes syphilis cannot be seen under a microscope or grown in a laboratory. Most cases are diagnosed by a blood test.
Symptoms: Syphilis progresses slowly. The first phase is a painless ulcer, usually on the genitals. Even without antibiotics, the ulcer heals, but after several weeks the person develops fever, a body rash, swollen glands and inflammation of various organs. This too settles down, but years later many people develop permanent damage to the heart, brain or other organs.
Treatment: Penicillin is the best treatment, but other antibiotics are available for penicillin-allergic patients.
Up to 75% of people infected with genital herpes don't know they have it.
Cause: This common infection is caused by the herpes simplex virus, usually type 2.
Symptoms: When symptoms develop, they include small, painful ulcers and blisters on the genitals and nearby tissues. Swollen glands, fever and headache are common, especially with the first episode. The herpes simplex virus makes its way to the nervous system where it stays throughout a person's lifetime. The virus can travel back down nerves to the skin, causing repeat attacks. Attacks tend to become milder and less frequent over the years. People with herpes can pass the virus to others who come in contact with their genital secretions, even if they don't have blisters or ulcers.
Treatment: There is no cure for genital herpes. The antiviral medications acyclovir, valacyclovir or famciclovir can reduce symptoms; long-term treatment can prevent spread of the infection, but can't eliminate the virus from your body. It's important to talk to your doctor or other health care professional about how to avoid infecting future partners.
Human Papillomavirus (HPV)
For years, doctors have known that HPV causes genital warts (condyloma) in men and women. In an exciting breakthrough, we now know that a few strains of HPV cause almost all cases of cancer of the cervix. HPV also plays a role in rare cancers in men, usually as a result of having sex with other men.
Symptoms: Most people who are infected with HPV don't know it. Others develop soft, moist, pink warts on the genitals or nearby tissues. Doctors can administer local treatments to clear up the warts, but the virus can still persist in the body for several years.
Treatment: A physician can apply medication directly to genital warts to help clear them up, but there are no treatments to cure the virus itself.
Prevention: The U.S. Food & Drug Administration has approved a vaccine that protects against the strains that cause genital warts and cervical cancer.
Most people don't think of hepatitis as an STI. That's understandable, since the infection harms the liver, not the sex organs, and since many cases are contracted non-sexually. But the major hepatitis viruses can also be spread by sex. Hepatitis B vaccine is recommended for all infants, for children who were not vaccinated in infancy, and for adults who are at risk.
Human Immunodeficiency Virus (HIV)
HIV can be transmitted sexually or by exposure to infected blood, semen and vaginal fluids. The virus attacks the immune system, which makes the body vulnerable to the devastating infections and cancers of AIDS.
Without treatment, it is almost always fatal. Medication can control, but not cure, HIV. There have been many medical advances in drug therapy for HIV. But it is demanding and expensive, and side effects are common.
Even so, HIV reminds us of the first and foremost rule for all STIs: Prevention is your first line of defense.
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Harvey B. Simon, M.D. is an Associate Professor of Medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men's Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men's Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.